Select what genuinely interests you. Your picks feed directly into our editorial planning. Bitcoin trades at $81,017 on Sunday evening, and the weekend’s most important number is not in the chart but in the protocol itself: since October 16 the network has demanded 5.92 percent more computing work for the same block. Mining difficulty climbed with block 971,712 to 140.58 trillion, its highest level since March 5. At the same time the price has fallen from $84,506 to $81,017 since the previous adjustment on October 3. More effort, less revenue: for miners that is the squeeze which ultimately decides how much they have to sell.